Triaryl phosphate functional fluids

ABSTRACT

THE PRESENT INVENTION RELATES TO A PROCESS AND COMPOSITION FOR TRANSMISSION OF PRESSURE IN A HYDRAULIC SYSTEM COMPRISING A MIXTURE OF A STYRENATED TRIARYL PHOSPHATE AND AN ALKYLPHENYL PHENYL PHOSPHATE.

United States Patent Int. Cl. C09k 3/00 US. Cl. 252-78 7 Claims ABSTRACTOF THE DISCLOSURE The present invention relates to a process andcomposition for transmission of pressure in a hydraulic systemcomprising a mixture of a styrenated triaryl phosphate and analkylphenyl phenyl phosphate.

BACKGROUND OF THE DISCLOSURE Functional fluids suitablefor the operationof hydraulic mechanisms require a combination of properties which areoften unattainable in many presently available materials. The propertieswhich are required for safe and satisfactory low temperature operationinclude a low pour point which permits a hydraulic fluid to operate atlow temperatures. Functional fluids should also exhibit low oxidativesusceptibility, thereby operating without the buildup of sludge. Anotherimportant property of such fluids is a fiat viscosity temperature curve,that is, a high viscosity index which allows the fluid to remainoperable over a wide rangeof temperatures. One of the vital propertieswhich is required for fluids which are to be utilized in either thecommercial and mining industries or in military use is minimumflammability. Still other desirable qualities for such products includea relatively high boiling point and low corrosive characteristics.

Mixtures of various phosphates have been employed as functional fluidsin the past. Triaryl and trialkyl phosphates have been utilized bythemselves or in combination with each other to yield functional fluidshaving a evariety of properties. However, the fluids of the prior artare deficient in one or more of the above properties.

It is an object of the present invention to provide functional fluidswhich exhibit all the desirable characteristics described above. I

It is a further object of the present invention to provide a totallysynthetic based functional fluid comprised of two components which, whencombined in varying proportions, give a series of fluids with varyingviscosities depending on the proportions; each having superiorcharacteristics to known fluids of similar viscosities.

It has now been discovered that these objects can be accomplished byemploying a functional fluid composition comprised of a styrenatedtriaryl phosphate and an alkylphenyl phosphate.

TECHNICAL DISCLOSURE THE INVENTION These fluids can also contain minoramounts of various additives such as antioxidants, rust inhibitors,defoamers, and load bearing additives.

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The styrenated triaryl phosphates employed in the present invention havea generic formula corresponding to:

(R1). H (B2)! '1 o alli. 0 4! Q o l o 5 6113/ I1 JX 3 wherein x is anumber from about 0.5 to about 2, and preferably from about 0.7 to about1.5 inclusive, n is a number from 1 to 3 inclusive, a and c are eachnumbers from 0 to 5 inclusive, b is a number from 0 to 4 inclusive, andR R and R are each an alkyl group having from 1 to about 8 carbon atoms.The compounds are characterized by high viscosities, that is,viscosities in excess of 900 Saybolt Universal Seconds at F. The valueof x is equal to the average number of styrylphenyl groups per phosphategroup. Thus, it designates a mixture of phosphates rather than a purecompound. For example, if the styrenated triaryl phosphate employed is astyrylphenyl phosphate having an x value of 1.5, and an n value of 1, itwill be comprised of a mixture of. styrylphenyl diphenyl phosphate,distyrylphenyl phenyl phosphate, triphenyl phosphate and various otherisomers; the mixture having an average value of 1.5 styrylphenyl groupsper phosphate group. Illustrative of the styrylphenyl compounds whichare preferred in the present invention are:

styrylphenyl diphenyl phosphate styrylphenyl dicresyl phosphatestyrylphenyl dixylyl phosphate styrylphenyl bis(isopropylphenyl)phosphate styrylphenyl bis(butylphenyl) phosphate isopropylbenzyl phenyldiphenyl phosphate and mixtures of the above With:

bis(styrylphenyl) phenyl phosphate bis(styrylphenyl) cresyl phosphatebis(styrylphenyl) xylyl phosphate and the like.

styrylphenyl diphenyl phosphate and styrylphenyl bis (isopropylphenyl)phosphate having an x value of 0.7 to 1.5 and an n value of l areparticularly preferred. Also included in the compounds of the presentinvention are:

distyrylphenyl diphenyl phosphate distyrylphenyl bis (isopropylphenyl)phosphate tristyrylphenyl diphenyl phosphate bis(distyrylphenyl) phenylphosphate distyrylphenyl dicresyl phosphate distyrylphenyl dixylenylphosphate and mixtures thereof.

The above mentioned compounds are meant to be illustrative only and arenot intended to be an inclusive listi 55 The alkylphenyl phosphatesemployed in the present invention have the formula corresponding to:

lcbv l -l -@lcosities will be below 200 Saybolt Universal Seconds at 100F. They are illustrate by the following: isopropylphenyl diphenylphosphate, bis isopropylphenyl phenyl phosphate, diisopropylphenyldiphenyl phosphate, tertbutylphenyl diphenyl phosphate, sec-butylphenyldiphenyl phosphate, hexylphenyl diphenyl phosphate, octyl phenyldiphenyl phosphate and mixtures thereof. Isopropylphenyl diphenylphosphate and the butylphenyl diphenyl phosphates are preferred.

The styrenated triaryl phosphates and alkylphenyl phosphates are blendedin proportions of from about to about 90 percent by weight of the entiremixture of the styrenated triaryl phosphate and from about 90 to about10 percent of the alkylphenyl phosphate. This blending is accomplishedby any of the known methods for blending fluids. The viscosity of theblend will vary over a wide range depending upon the particularphosphates used and the proportions in which they are blended.Therefore, by varying the relative proportions of the two phosphatesemployed, a series of fluids having different viscosities can beobtained from only two components. Normally, these fluids will haveviscosities in the range of from about 100 to about 900 SayboltUniversal Seconds and preferably from about 220 to about 600 SayboltUniversal Seconds at 100 F.

The fluids of the present invention are characterized by exceptionallyhigh oxidative stability, low pour points, high autoignitiontemperatures and relatively high viscosity indices when compared withthe fluids known in the art. Furthermore, the fluids of the presentinvention exhibit excellent flame retardancy and hydrolytic stability.

The fluids of the present invention can also contain minor amounts ofother additives which are well known in the art. While, the fluids ofthe present invention have excellent oxidative stability by themselves,this property can be enhanced by the addition of any of the commonlyused antioxidants such as the aryl amines, alkyl phenols, naphthylamines, and alkylphenyl amines.

The naphthyl amines, such as phenyl-a-naphthyl amine andoctylphenyl-a-naphthyl amine, and the alkyl phenyl amines, such asdioctyl diphenyl amine, are particularly useful antioxidants in thefluids of the present invention. These antioxidants are normally blendedin amounts from about 0.1 to about 2 percent by weight. Rust inhibitorssuch as the polyhydric alcohols, alkyl malonic and succinic acids,amines, aminophenols and the polyvalent metal salts of organo sulfonicacid can also be incorporated in the fluids of the present invention.These rust inhibitors are also used in relatively small proportions,that is, from about 0.1 to about 2 percent by weight. Foam depressantscan also be incorporated in the fluids.

The functional fluids of the present invention are deployed in closedhydraulic systems such as compressors, hydraulic lifts, deck edgeelevators, brake systems, basic oxygen furnaces, die casting equipment,leveling devices or servo control units in such a manner that whenpressure is applied to the fluid at a specific point within the confinesof the hydraulic system, the pressure will be transmitted to every otherpoint along the hydraulic system by the fluid.

The invention will be further illustrated by the following examples.

Example 1 Styrylphenyl bis(isopropylphenyl) phosphate was synthesized byreacting a commercially available styrenated phenol with phosphorusoxychloride in the presence of magnesium chloride, and then reacting theproduct so obtained with a commercially available isopropylated phenol.The product contained an average of approximately 0.7 styrylphenylgroups per molecule and had a viscosity of 1009 Saybolt UniversalSeconds at 100 F. This styrenated phenyl bis(isopropylphenyl) phosphatewas blended with the isopropylphenyl diphenyl phosphate in approximately42 and 5 8 percent respectively by weight 4 of the entire composition.The fluid exhibited the properties contained in Table I.

Hot manifold (drip) ignition: Temperature F.) 1480 Shell 4 ball test (54C., 600 r.p.m.):

10 kg. 0.30 40 kg. 0.50

Example 2 Styrylphenyl diphenyl phosphate was synthesized by reacting acommercially available styrenated phenol with phosphorus oxychloride inthe presence of magnesium chloride and then reacting the product soobtained with phenol. The product contained an average of slightlygreater than 1 styrylphenyl groups per molecule and had a viscosity of1033 Saybolt Universal Seconds at F. This styrylphenyl diphenylphosphate was blended with isopropylphenyl diphenyl phosphate inapproximately 42 and 58 percent respectively by weight of the entirecomposition. The fluid exhibited the properties contained in ab e II.

TABLE II Viscosity (Saybolt Universal Seconds) At 100 F. 219 At 210 F.44 Viscosity index 28 Acidity (mgs. KOH/gm.) 0.04 Autoignitiontemperature F.) 1120 Flash point F.) 275 Fire point F.) 650 Similartests were conducted on a commercially available functional fluid soldunder the tradename of Fyrquel 220 by Stauifer Chemical Company of NewYork. Fyrquel 220 is a triaryl phosphate based fluid having a viscosityof approximately 220 Saybolt Universal Seconds at 100 F. The fireproperties were approximately the same for the styrylphenyl diphenylphosphate fluid and Fyrquel 220 but the styrylphenyldiphenyl phosphatehad a considerably higher viscosity index, thereby affordgig it a widerrange of application than the commercial uid.

Example 3 The fluid employed in Example 2 was tested in a Vickers vanepump according to the procedure outlined in ASTM-D2271. A total volumeof 9.5 gallons was employed and the temperature was maintained at F.under a pressure of 2000 p.s.i. The results are contained in Table III.

TABLE III Total ring Total vane Acid number weight weight Viscosity (mm. Time, hours loss (grn.) loss (gm.) (S.U.S.) KOH/gm.)

Table III demonstrates that the fluids of the present invention maintaintheir viscosity and acidity characteristics within close tolerances overlong periods of continuous use with very little corrosive eflect on theequipment.

Example 4 A series of fluids were prepared by varying the proportions ofthe styrylphenyl diphenyl phosphate and the isopropylphenyl diphenylphosphate employed in Example 2.

The relative proportions are contained in Table IV. TABLE IVIsopropylphenyl diphen- Styrylphenyl phosphate Viscosity diphenylphosphate (percent by 100 F. (percent by weight) weight) (S.U.S.)

All of the blends in Table IV exhibit relatively low acidity, highviscosity and comparable fire properties when compared with commercialfluids having similar viscosities.

What is claimed is:

1. A synthetic hydraulic fluid composition consisting essentially of:

(a) from about 10% to about 90% by weight of the entire composition of astyrenated triaryl phosphate having the formula corresponding to:

(T1): H 1 2)!) o I" l H O -o- P J. L

wherein x is a number from about 0.5 to about 2.0

wherein R is an alkyl group having, from 3 to about 12 carbon atoms, dis a number from 1 to 5 inclusive, and y is a number from about 0.2 toabout 2.5 inclusive; said composition having a viscosity in the rangefrom about 100 to about 900 Saybolt Universal Seconds at 100 C.

(Rah

2. The composition of claim 1 wherein n is '1 and x is a number fromabout 0.7 to about 1.5.

3. The composition of claim 1 wherein the styrenated triaryl phosphateis styrylphenyl diphenyl phosphate. 5 4. The composition of claim 1wherein the styrenated triaryl phosphate is styrylphenylbis(isopropylphenyl) phosphate.

5. The composition of claim 4 wherein the alkylphenyl phosphate isisopropylphenyl diphenyl phosphate.

6. The composition of claim 1 wherein the alkylphenyl phosphate ischosen from the group consisting of tertbutylphenyl diphenyl phosphateand sec-butylphenyl diphenyl phosphate.

7. A process for the transmission of pressure in a hydraulic systemwhich comprises deploying within said hydraulic system an effectiveamount of a hydraulic fluid composition consisting essentially of:

(a) A styrenated triaryl phosphate having the formula corresponding to:

o Q 0 l 0 Ha/n .|x L 3-x wherein x is a number from about 0.5 to about2.0 inclusive, n is a number from 1 to 3 inclusive, a and c are eachnumbers from 0 to about 5, b is a number from 0 to 4 inclusive, and R Rand R are each alkyl groups having from 1 to about 8 carbon atoms; 30and (b) An alkylphenyl phosphate having the formula 7 corresponding to:

wherein y is a number from about 0.2 to about 2.5 and R is an alkylgroup having from 1 to about 12 carbon atoms; and applying pressure tosaid hydraulic fluid composition at any point in said system so as tothereby transmit the thus applied pressure throughout said systemthrough the medium of said hydraulic fluid composition.

US. Cl. X.R.

